The present invention relates to a steering gear apparatus and, more specifically, to a boot seal and a steering gear tie rod associated with the boot seal.
A conventional rack and pinion steering apparatus for a vehicle has a ball joint connecting a rack to a tie rod and a bearing that supports a rack for movement relative to a housing. A boot seal seals against the housing and the tie rod. If the boot seal does not properly seal against the housing or the tie rod, dirt, water and other contaminants may enter the boot seal. If this occurs, operation of the steering gear may be affected. A long lasting and inexpensive boot seal that effectively seals against the housing and tie rod over a long period of time is desirable.
Typically, a boot seal is made with an internal diameter smaller than the outer diameter of the part on which it is to seal. This requires some stretching of the boot seal in order to engage the part. The materials of which some boot seals are made do not recover one-hundred percent (100%) after stretching. Also, the materials of which some boot seals are made are not readily compressible. Accordingly, such a boot seal, if stretched prior to installation, may not completely seal entirely around the part.
In some systems the part, for example a tie rod for a vehicle steering system, may have a circumferential groove machined into the part and the boot seal may have a ring of material on its internal diameter to be located in the groove. The diameter of the ring must be stretched over the tie rod and then spring back to fit into the groove. In these systems, there is a potential for an inadequate seal. Accordingly, it would be desirable to provide a boot seal for a tie rod that may be installed with a minimum of stretching of the boot seal.
In accordance with the present invention, an apparatus includes a tie rod for a vehicle steering system and a boot seal. The tie rod has a longitudinal axis, a first cylindrical portion with a first outer surface of a first diameter, and a second cylindrical portion coaxial with the first cylindrical portion. The second cylindrical portion has a second outer surface of a second diameter. The second diameter is smaller than the first diameter. The tie rod has a ring portion projecting radially from the second outer surface of the second cylindrical portion. The ring portion extends circumferentially completely around the axis of the tie rod. The ring portion is spaced axially from the first cylindrical portion. The ring portion has a third outer surface extending axially along the second cylindrical portion. The boot seal encircles the second cylindrical portion. The boot seal has a sealing surface in sealing contact with the third outer surface of the ring portion. The sealing surface of the boot seal defines a groove in the boot seal. The ring portion of the tie rod is located in the groove.
In accordance with another feature of the present invention, an apparatus includes a tie rod for a vehicle steering system and a boot seal. The tie rod has a longitudinal axis, a first cylindrical portion with a first outer surface of a first diameter, and a second cylindrical portion coaxial with the first cylindrical portion. The second cylindrical portion has a second outer surface of a second diameter. The second diameter is smaller than the first diameter. The boot seal encircles the second cylindrical portion. The tie rod has a torus-shaped ring portion projecting radially from the second outer surface of the second cylindrical portion. The torus-shaped ring portion extends circumferentially completely around the axis of the tie rod. The torus-shaped ring portion is spaced axially from the first cylindrical portion. The ring portion has a third outer surface extending axially along the second cylindrical portion. The torus-shaped ring portion curves radially outward from axially spaced locations on the second outer surface of the second cylindrical portion. The boot seal has a sealing surface in sealing contact with the third outer surface of the torus-shaped ring portion. The sealing surface of the boot seal defines a groove in the boot seal. The torus-shaped ring portion of the tie rod is located in the groove.
In accordance with still another feature of the present invention, an apparatus includes a tie rod for a vehicle steering system and a boot seal. The tie rod has a longitudinal axis, a first cylindrical portion with a first outer surface of a first diameter, and a second cylindrical portion coaxial with the first cylindrical portion. The second cylindrical portion has a second outer surface of a second diameter. The second diameter is smaller than the first diameter. The boot seal encircles the second cylindrical portion. The tie rod has a ring portion projecting radially from the second outer surface of the second cylindrical portion. The ring portion extends circumferentially completely around the axis of the tie rod. The ring portion is spaced axially from the first cylindrical portion. The ring portion has a third outer surface extending axially along the second cylindrical portion. The ring portion comprises at least part of male threads extending radially from the second cylindrical portion. The boot seal has a sealing surface in sealing contact with the third outer surface of the ring portion. The sealing surface of the boot seal defines a groove in the boot seal. The ring portion of the tie rod is located in the groove. The groove comprises at least part of female threads engaging the male threads of the tie rod.